FIG. 12 shows a schematic view of a conventional frequency analyzer. When utilizing a conventional frequency analyzer, an analogue input signal V(t), whose frequency is to be analyzed, is first converted by an AD converter 1 to obtain digitized time base data. The time base data is stored in memory 2 and transferred to a window function weighting means 3 when needed. The weighting function is performed by multiplying the window function weighting means 3, for example the Hann window function, by the time base data. The weighted time base data is then input to in a Fast Fourier Transform (FFT) means 4. The time base data is transformed to the frequency domain data S(f) utilizing the FFT means. The frequency domain data S(f) is subsequently input to a display device 5. Finally, the frequency spectrum of the analogue input signal V(t) is displayed therein.
The following disadvantages are associated with the conventional frequency analyzer described above. First, if the time base data stored in memory 2 is set at T(second), the resolution of the analysis spectrum is 1/T(Hz). As a result, the frequency spectrum cannot be displayed at higher resolutions.
Second, the vector analysis-frequency obtained by the FFT means 4 is discrete [n/T(Hz): n is an integer]. If the frequency spectrum of the analogue input signal V(t) does not match n/T(Hz), the amplitude value of the analyzed frequency spectrum may be adversely altered.
Third, when performing a spectrum analysis utilizing a FFT means 4, there is no significance in having an absolute phase. In other words, the absolute phase of the spectrum cannot be measured utilizing FFT means.
The object of the present invention is to overcome the above listed disadvantages and provide a high resolution frequency analyzer, having higher resolution than conventional analyzers, which can precisely measure the amplitude and phase of the spectrum.